The detection and identification of explosives hidden on the surface or buried under the ground has a multitude of commercial applications. After Sep. 11, 2000 the United States proclaimed war on the terrorists responsible for the attack on the Twin Towers in New York City. This included those directly involved as well as those who actively aided in the attack. Military intelligence from a number of sources identified specific individuals including the then ruler of Iraq. In previous United Nations investigations of Iraq sanctions were instituted against the country and its ruler to force compliance with international nuclear weapons reduction treaties. When attempts failed the United States invaded Iraq. During the attack and during the Iraq occupation non-conventional weapons were used by the insurgence to retaliate against United States forces. These devices were called improvised explosive devices or “IED”s. Because of their non-conventional appearance they were difficult to identify and consequently caused a number of casualties. Currently a number of methods exist for the detection of IED's including (1) Ground Penetrating Radar, which does not meet performance targets established by the military, (2) Electrical Impedance Tomography, which requires physical contact with the ground and which cannot be used in very dry soil, (3) X-Ray Backscatter, which is physically large, consumes large power and which requires high X-ray power to operate, (4) Acoustic-Seismic device, which is not effective when surface vegetation is present, (5) Chemical Vapor detection system, which is not sensitive to very low chemical density, (6) Biological method where mammals like dogs do not perform well under fatigue, (7) Nuclear Quadrupole Resonance, which is effective only at high signal-to-noise ratios, (8) Prodders and Probes, which are risky due to the possibility of detonation, (9) Thermal Signature Detection using analytical models, which requires soil-specific parameters such as heat capacity, soil density and thermal conductivity and which requires intensive iterative computations that may be unstable. Most of these existing methods either make physical contact with the ground or are not reliable.
Consequently there is a need for a multispectral imaging system that can detect, identify, locate and classify explosives such as improvised explosive devices (IEDs) both hidden on the surface or buried below the surface of the ground that is more reliable than current methods, does not require substantial amounts of energy to operate and does not require physical contact with the soil.